1

Hands-on Workshop on

Open vSwitch and Software-defined Networking

Ali AlSabeh, Jorge Crichigno

University of South Carolina

http://ce.sc.edu/cyberinfra

aalsabeh@email.sc.edu, jcrichigno@cec.sc.edu

WASTC 2021 virtual Faculty Development Weeks (vFDW)

June 22, 2021

Interconnection between legacy networks and SDN networks

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Potential Drawbacks of SDN

• SDN networks have many advantages over traditional networks • Ease of network management

• Enforcement of security policies

• Customized network behavior

• However, SDN is typically not fully deployed in networks due to several reasons • Limited budget for new network infrastructure

• Fear of downtime during the transition to SDN

• Limited training opportunities in SDN technology

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R. Amin, M. Reisslein, N. Shah, Hybrid SDN networks: A survey of existing approaches, IEEE CST, Vol. 20, Issue: 4, 2018.

Potential Drawbacks of SDN

• One possible solution to address these concerns is to deploy a limited number of

SDN-enabled devices alongside the traditional (legacy) network devices

• Incrementally replacing traditional network devices by SDN devices

• The network can be converted in stages, targeting specific network areas for

conversion and rolling out the changes incrementally • A network containing a mix of SDN and legacy network devices is referred to as a hybrid SDN network

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Advantages of Hybrid SDN Networks

• Hybrid SDN networks ease these budget concerns • Cost of replacing legacy devices by SDN devices

• Train engineers to design, configure, and operate the SDN network

• SDN provides fine-grained control for data traffic flows • If this is required for a small network portion, then SDN can be implemented in that portion only

• Scenarios where two SDN networks are interconnected by legacy network devices

require hybrid SDN network mechanisms

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Border Gateway Protocol

• The Border Gateway Protocol (BGP) version 4 is the standard inter-autonomous

system (AS) protocol in today’s Internet • An AS is a group of routers typically under the same administrative control (e.g., ISP, company)

• BGP is the “glue that holds the Internet together”

• In BGP, pairs of routers exchange routing information over TCP (default port 179)

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J. Kurose, K. Ross, Computer Networking: A Top-Down Approach, 7th Edition, Pearson/Addison Wesley, 2017.

Border Gateway Protocol

• BGP provides each AS a means to: • eBGP: obtain subnet reachability information from neighboring ASes

• iBGP: propagate reachability information to AS-internal routers

• Determine “good” routes to other networks based on reachability information and policy

• Allows subnet to advertise its existence to rest of Internet: “I am here”

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J. Kurose, K. Ross, Computer Networking: A Top-Down Approach, 7th Edition, Pearson/Addison Wesley, 2017.

Lab 8: Interconnection between legacy networks and SDN networks

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Lab 8: Interconnecting Legacy and SDN networks • Two legacy networks connected to an

SDN network

• SDN network consists of switches

controlled by an ONOS controller

• The ONOS controller interacts with an

application referred to as SDN-IP

• SDN-IP allows the SDN network to i)

exchange BGP information with an iBGP

router; and ii) translates routing

information to SDN flow rules

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c0

h1

r1

r2 r3

s2 s3

s1

r2-eth0

s4-eth2

s4

s4-eth1

h1-eth0

h2

r3-eth0

s5-eth2

s5

r5-eth1

h2-eth0

r2-eth1 r1-eth0

s1-eth1s2-eth1

r3-eth1

s3-eth1s3-eth2

s1-eth2s1-eth3

s2-eth2

192.168.2.0/24 192.168.3.0/24

.1

.10

.1

.10

192.168.12.2/30 192.168.13.2/30

AS 200

AS 100

AS 300

10.0.0.1/24

10.0.0.3/24

Out-of-band connection

r1-eth1

192.168.12.1/30

192.168.13.1/30

Lab 8: Interconnecting Legacy and SDN networks

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1. Routers r2 and r3 attempt to connect to r1 (eBGP)

2. Switches s2 and s3 forward incoming packets to controller

3. Controller installs rules to forward those BGP packets to r1

4. Router r1 exchanges BGP information to controller (iBGP)

5. Controller translates BGP information into rules

6. Rules are installed in s1, s2, and s3 (remote networks)

7. Full connectivity is established

c0

h1

r1

r2 r3

s2 s3

s1

r2-eth0

s4-eth2

s4

s4-eth1

h1-eth0

h2

r3-eth0

s5-eth2

s5

r5-eth1

h2-eth0

r2-eth1 r1-eth0

s1-eth1s2-eth1

r3-eth1

s3-eth1s3-eth2

s1-eth2s1-eth3

s2-eth2

192.168.2.0/24 192.168.3.0/24

.1

.10

.1

.10

192.168.12.2/30 192.168.13.2/30

AS 200

AS 100

AS 300

10.0.0.1/24

10.0.0.3/24

Out-of-band connection

r1-eth1

192.168.12.1/30

192.168.13.1/30

Configuring BGP in Legacy Networks

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Router r2

Router r3

c0

h1

r1

r2 r3

s2 s3

s1

r2-eth0

s4-eth2

s4

s4-eth1

h1-eth0

h2

r3-eth0

s5-eth2

s5

r5-eth1

h2-eth0

r2-eth1 r1-eth0

s1-eth1s2-eth1

r3-eth1

s3-eth1s3-eth2

s1-eth2s1-eth3

s2-eth2

192.168.2.0/24 192.168.3.0/24

.1

.10

.1

.10

192.168.12.2/30 192.168.13.2/30

AS 200

AS 100

AS 300

10.0.0.1/24

10.0.0.3/24

Out-of-band connection

r1-eth1

192.168.12.1/30

192.168.13.1/30

Configure BGP in SDN Network

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Router r1

c0

h1

r1

r2 r3

s2 s3

s1

r2-eth0

s4-eth2

s4

s4-eth1

h1-eth0

h2

r3-eth0

s5-eth2

s5

r5-eth1

h2-eth0

r2-eth1 r1-eth0

s1-eth1s2-eth1

r3-eth1

s3-eth1s3-eth2

s1-eth2s1-eth3

s2-eth2

192.168.2.0/24 192.168.3.0/24

.1

.10

.1

.10

192.168.12.2/30 192.168.13.2/30

AS 200

AS 100

AS 300

10.0.0.1/24

10.0.0.3/24

Out-of-band connection

r1-eth1

192.168.12.1/30

192.168.13.1/30

SDN-IP Application

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ONOS CLI – BGP neighbors c0

h1

r1

r2 r3

s2 s3

s1

r2-eth0

s4-eth2

s4

s4-eth1

h1-eth0

h2

r3-eth0

s5-eth2

s5

r5-eth1

h2-eth0

r2-eth1 r1-eth0

s1-eth1s2-eth1

r3-eth1

s3-eth1s3-eth2

s1-eth2s1-eth3

s2-eth2

192.168.2.0/24 192.168.3.0/24

.1

.10

.1

.10

192.168.12.2/30 192.168.13.2/30

AS 200

AS 100

AS 300

10.0.0.1/24

10.0.0.3/24

Out-of-band connection

r1-eth1

192.168.12.1/30

192.168.13.1/30

SDN-IP Application

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ONOS CLI – advertised routes c0

h1

r1

r2 r3

s2 s3

s1

r2-eth0

s4-eth2

s4

s4-eth1

h1-eth0

h2

r3-eth0

s5-eth2

s5

r5-eth1

h2-eth0

r2-eth1 r1-eth0

s1-eth1s2-eth1

r3-eth1

s3-eth1s3-eth2

s1-eth2s1-eth3

s2-eth2

192.168.2.0/24 192.168.3.0/24

.1

.10

.1

.10

192.168.12.2/30 192.168.13.2/30

AS 200

AS 100

AS 300

10.0.0.1/24

10.0.0.3/24

Out-of-band connection

r1-eth1

192.168.12.1/30

192.168.13.1/30

SDN Network

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BGP table of router r1 c0

h1

r1

r2 r3

s2 s3

s1

r2-eth0

s4-eth2

s4

s4-eth1

h1-eth0

h2

r3-eth0

s5-eth2

s5

r5-eth1

h2-eth0

r2-eth1 r1-eth0

s1-eth1s2-eth1

r3-eth1

s3-eth1s3-eth2

s1-eth2s1-eth3

s2-eth2

192.168.2.0/24 192.168.3.0/24

.1

.10

.1

.10

192.168.12.2/30 192.168.13.2/30

AS 200

AS 100

AS 300

10.0.0.1/24

10.0.0.3/24

Out-of-band connection

r1-eth1

192.168.12.1/30

192.168.13.1/30

Legacy Network

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Routing table of router r2 c0

h1

r1

r2 r3

s2 s3

s1

r2-eth0

s4-eth2

s4

s4-eth1

h1-eth0

h2

r3-eth0

s5-eth2

s5

r5-eth1

h2-eth0

r2-eth1 r1-eth0

s1-eth1s2-eth1

r3-eth1

s3-eth1s3-eth2

s1-eth2s1-eth3

s2-eth2

192.168.2.0/24 192.168.3.0/24

.1

.10

.1

.10

192.168.12.2/30 192.168.13.2/30

AS 200

AS 100

AS 300

10.0.0.1/24

10.0.0.3/24

Out-of-band connection

r1-eth1

192.168.12.1/30

192.168.13.1/30